Twenty lawmakers are calling for funding to keep the Air Force's A-10 close-air support aircraft flying to be included in any budget deal for fiscal 2018.

The fleet has been used to attack Islamic State fighters, but about one-third of the aging 1970s-era aircraft, also known as Warthogs, are in need of wing replacements.

The maintenance work on 110 of the A-10s was included in the National Defense Authorization Act signed this week by President Trump. But Congress has yet to reach an agreement to fund the annual defense bill and the Senate’s defense appropriations plan for fiscal 2018 so far does not include the money for new wings.

“We ask that this same level of funding [as the NDAA] be secured in any final FY18 spending package in order to prevent a critical capability gap in the operational fleet,” Rep. Martha McSally, R-Ariz., a former A-10 pilot, along with 18 House members and a senator wrote in a letter to congressional appropriators.

The Air Force had recently moved to retire the Warthog, but it has been saved over the last few years by McSally and fellow members of Congress, who argue its close-air support capabilities are still needed on the battlefield.

The $103 million re-winging effort comes after the Air Force agreed to keep the aircraft indefinitely.

“Now that the Air Force has confirmed that it plans to maintain the A-10 fleet well into the foreseeable future, the remaining 110 wing sets must be delivered as soon as possible,” the lawmakers wrote in the letter to the chairmen and ranking members of the House and Senate appropriations committees.